The present invention relates to a moldable dental composition which can firmly be bound and cured in a short time interval at room temperature. The present invention provides dental compositions which are especially useful as filling materials for the pulp canal, temporal filling materials for broken teeth, temporal cements for metal inlays or crowns, impression materials for obtaining a negative of the hard and soft tissues of the oral cavity, fixing materials for correcting the irregularities of the teeth, restorative materials for dentures or materials for other therapeutic uses.
Heretofore, for such purposes, use has long been made of a zinc oxide/eugenol based material composed mainly of eugenol or clove oil, resin and zinc oxide, which is separated into two component phases, liquid and powder components or is cured by kneading two components, paste and other paste. This material is disadvantageous in that the eugenol gives out a peculiar bad odor, and has a stimulating action on the hard and soft tissues of the oral cavity. Accordingly, when this material is used as an impression material for obtaining an impression of the hard and soft oral tissues, it sometimes comes in contact with the oral mucosa of a patient to causes severe pain to the patient and, in particular, causes intolerable pain to a patient whose mouth is inflamed or injured.
In addition, special care must be taken of allergic patients or dental surgeons since, even when they merely touch this material, it brings about an allergic reaction to them.
Furthermore, the supply of eugenol depends on the situation of affaires in the Western Africa, a main producer of eugeno. Hence, its price is precarious and high.
For these reasons, extensive investigations have been made for a long time on a novel material which is substantially free from any eugenol, but is still equivalent or superior thereto. For example, Japanese Patent Publication No. 246l0/l96l describes that a composition which is similar in performance to a reaction product of zinc oxide and eugenol is obtained by saponifying an aliphatic carboxylic acid of the middle class with the use of a metal oxide to form an insoluble metallic soap. Since the saponification reaction proceeds slowly in this case, however, it is required to activate the reaction with the aid of a lower fatty acid and under the presence of a considerable amount of a resin acid such as rosin, leading to an excessive increase in the consistency of the resultant formulation. As a result, the formulation offers marked resistance to kneading. In addition, when a relatively lower fatty acid is used so as to raise the reactivity of the resultant composition, the composition is liable to emit an offensive odor peculiar to the lower fatty acid.
On the other hand, the use of a higher fatty acid was disadvantageous in that it does not only lower the reactivity of the composition, but also raises the melting point thereof when it is formulated in the form of paste, thus rendering it difficult to employ the same at lower temperatures.